Research backs Grandpa’s old crop rotation

Saturday, November 10, 2012 - 10:26 am

Life seems to bounce from one hard lesson to the next.

Recent research by the U.S. Department of Agriculture, University of Minnesota and Iowa State University confirms what your father and grandfather told you: “The more things change, the more they stay the same.”

The research, published in several formats this fall, show that three-year and four-year crop rotations that include a small grain like oats and a forage such as red clover and alfalfa produce not only as good or better yields per acre than today's dominant corn-soybeans rotation but also dramatically cut energy use per acre and manage weeds effectively while slashing fertilizer and herbicide use.

The research was conducted on 22 acres of prime Iowa farmland over nine years, from 2003 through 2011. Its goal was to “explore the potential benefits of diversifying cropping systems” to better manage pests, “improve resource efficiencies” and “enhance other agroecosystem processes.”

The three rotations were a two-year corn/soybean system; a three-year corn/soybean/small grain plus red clover plan; and, finally, a four-year corn/soybeans/small grain plus alfalfa/alfalfa rotation. The latter two featured triticale as the small grain from 2003 to 2006; oats replaced it from 2006 through 2011.

The results, reported as the trials were ongoing and in at least two publications this fall (link to both at www.farmandfoodfile.com), were striking.

For example, according to an Iowa State University Extension bulletin published in September, the two-year corn/soybean rotation produced a glittering average of 193.7 bushels of corn and 50.3 bushels of beans from 2006 through 2011.

The three-year, corn/soybean/oats rotation across those same years produced even better average yields – 199.8 bushels of corn, 54.73 bushels of soybeans and 97.9 bushels of oats. The four-year rotation, however, was killer: 202.4 on corn, 56.9 on soybeans, 101.6 for oats and almost 4 tons of alfalfa in its first full year.

Profit per acre was equally striking. The ISU paper breaks out profit in three categories. First is the classic “Land, Labor, Management” figure, next “Land & Management” and finally, “Management.”

The two-year rotation's average per acre “Return to Management” from 2006 to 2011 was $188. Similarly the average for the three-year rotation was $194 per acre, and the four-year rotation averaged $170 per acre. The three- and four-year rotations, though, carried big savings in production costs. For instance, each used less than half the BTUs – calculated by totaling fuel, fertilizer, grain drying, “field operations” and pesticides – than the two-year rotation. When put in terms of gallons of fuel used across the rotations, the two-year system “uses the equivalent of 25.43 gallons of diesel fuel per acre (while the)… three- and four-year rotations are both just over 10 gallons per acre.”

So, what's the catch? You have to farm like your father and grandfather. Longer rotations; use of livestock manure; hay baling; moldboard plow the alfalfa; and, yep, retrieve that cultivator.

The study's point, says Liebman, is clear: “There is an attainable balance between high productivity, conservation and profitability.”